Machine tools utilizing relative motion between the spindle and tool slide for performing boring, contouring and threading work have long been known in the art. Machines of this type are shown, for example, in the following U.S. and foreign patents:
______________________________________ U.S. Pat. No. Patentee U.S. Pat. No. Patentee ______________________________________ 2,157,248 Swanson 3,592,553 Heizer 2,404,433 Christman 3,686,964 Thibaut et al. 2,430,026 Mealey 3,902,386 Dressler et al. 2,495,583 Heron 4,250,775 Jerue et al. 2,775,147 Schneebeli et al. U.S.S.R. 309,576 3,113,475 Lombardo W. Ger. 2,405,694 3,228,265 Stoddard et al. ______________________________________
Many of these prior devices are unduly complicated. Some are primarily manually actuated and require frequent adjustment. Some are not sufficiently accurate to produce work that would be considered acceptable by current manufacturing standards. Still others do not readily lend themselves to operation under numerical control.